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Microorganism there are minimum, optimum and maximum
water activity same like pH and temperature. Therefore, lowering water activity
(aw) can minimize putrefaction and improve preservation of fish. The term water
activity (aw) refers to the water which is not bound to food molecules and can
support the growth of bacteria, yeasts and moulds (fungi). The water activity
(aw) represents the ratio of the water vapor pressure of the food to the water
vapor pressure of pure water under the same conditions and it is expressed as a
fraction .The control of water activity is accomplished by drying, adding
chemicals, or a combination of both methods. Sugars and sodium chloride have
been used to bind up the free water molecules and create an osmotic imbalance
resulting in cell growth inhibition.
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